This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. ABSTRACT The recent approval by the FDA of the quadrivalent meningococcal conjugate vaccine (MCV4) has led to a recommendation to vaccinate 11-12 year-old individuals at a pre-adolescent visit, individuals entering high school (approximately 15 years of age) and incoming college freshman living in dormitories, in recognition of the increased meningococcal disease risk during adolescence. As the majority of children with perinatally acquired HIV infection have aged into adolescence, and the majority of new pediatric HIV infections in the US are occurring in the adolescent age group, the new age-based recommendations for meningococcal immunization patients will lead to most HIV-infected youth being age-eligible for a vaccine for which there are no safety or immunogenicity data available from HIV-infected populations. This phase I/II study will evaluate the safety and immunogenicity of MCV-4 in 296 HIV-infected youth between =11 and 15);To estimate the long-term (at 72 weeks) immunogenicity of the MCV4 vaccine in HIV-1 infected youth;To evaluate the safety of the MCV4 vaccine in HIV-1 infected youth, including short-term local and systemic reactions following administration of the vaccine.